Europeans always believed that africa was a storehouse for precious metals. Marine technology was very helpful to portuguese in terms of finding new routes to other continents through water. They also used some help from ancient greeks and also had help from muslim mariners who shared their experience of africa and the indian ocean. Chinese invention of gun powder helped them, the ottomans and also christians in order to conquer different continents or nations. English king won the battle against french with less than 10,000 men in 1415, and by 1492, the. Spanish crown amassed a huge force of 60,000 soldiers. Africa and other islands proved to be far more than just storehouses for metals since those islands were the main locations where sugar cane could be grown portuguese established over there, built their fortresses and ports. Started exploiting african slave labor from their mainland.